Tamper-evident cap and container neck

ABSTRACT

A tamper-evident, snap-on, screw-off closure is used with a specially shaped container neck. The neck has at least one first helical thread on an upper neck stretch portion, and at least one external ratchet tooth on a locking wall portion below the upper neck stretch portion. The closure has an upper skirt having at least one second helical thread mating with the first helical thread of the neck. A downward extending lower skirt portion includes an outer skirt portion and a shoulder extending inwardly from said outer skirt portion. A frangible section interconnects the shoulder and the upper skirt portion. At least one substantially vertical castle projection is formed upstanding from the shoulder, preventing upward deformation of the lower skirt portion without breaking the frangible section. The lower skirt portion has at least one internal ratchet tooth, and is formed with a line of weakness extending through the outer skirt portion and the shoulder. The lower skirt has a tear tab which, when pulled, fractures the lower skirt on a vertical line. Continued pulling on the tab sequentially fractures the frangible section.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 10/668,780 filed Sep. 22, 2003, which is a continuation of U.S.patent application Ser. No. 10/210,716, filed Jul. 30, 2002 and now U.S.Pat. No. 6,637,611, which is a continuation of U.S. patent applicationSer. No. 09/746,882 filed Dec. 22, 2000 and now U.S. Pat. No. 6,439,412,which is a continuation of U.S. patent application Ser. No. 09/356,063filed Jul. 19, 1999 and now U.S. Pat. No. 6,173,853, which is acontinuation of U.S. patent application Ser. No. 09/071,625 filed May 1,1998 and now U.S. Pat. No. 5,975,321, which is a continuation-in-part ofU.S. patent application Ser. No. 08/781,453, filed Jan. 10, 1997 and nowU.S. Pat. No. 5,755,348, which is a continuation of U.S. patentapplication Ser. No. 08/456,741 filed Jun. 1, 1995 and now abandoned,which is a divisional of Ser. No. 08/029,177 filed Mar. 10, 1993 and nowU.S. Pat. No. 5,456,376, which is a continuation-in-part of U.S. patentapplication Ser. No. 07/830,133 filed Jan. 31, 1992 and now U.S. Pat.No. 5,267,661, which is a continuation-in-part of U.S. patentapplication Ser. No. 07/772,945 filed Oct. 8, 1991 and now U.S. Pat. No.5,213,224, which is a continuation-in-part of U.S. patent applicationSer. No. 07/565,638 filed Aug. 9, 1990 and now U.S. Pat. No. 5,190,178,the entire contents of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a new and improved container closure andcontainer neck structure and more particularly to a structure whereinthe closure is applied with a single one-dimensional axial downwardforce onto the neck and is held in such position by a tamper-evidentband. The consumer destroys a frangible connection between the cap andthe band during initial removal, preferably by tearing away the bandenabling the closure to be unscrewed from the container neck. When thecap is used for reclosure purposes, it may be screwed on and screwed offin the same manner as screw caps have heretofore been used.

2. Description of Related Art

Prior snap-on, screw-off structures may be classified under either ofthe following categories: (1) Those with thread engagement as initiallyapplied; and (2) Those without.

The major advantages of the no-thread initial engagement systems arethat they are conceptually simple, careful alignment of the closure andthe container is not necessary upon application of the closure, and easy(low force) application is possible since no thread-jumping is required.This version can be an aesthetically pleasing, straight wall cap design,and good re-seal is achieved on reclosure because of the torqueadvantage of threads. On the other hand, the disadvantages of such asystem are that it may be confusing to the consumer because initialremoval is merely by lifting the cap off the neck but subsequent userequires twisting the cap relative to the neck. Further, it is difficultto use the system with a lined closure because of the heightrelationships between the finish and the cap, and finally the cap mustbe relatively tall, which forces the use of fine threads, which can bedifficult to mold. None of these disadvantages are present in thisinvention.

A closure such as Crisci U.S. Pat. No. 4,561,553 has a number ofproblems. The tamper evident feature of the closure may be circumventedby being able to engage the threads of the neck and closure (therebycreating a mechanical advantage) and back off the cap while thetamper-evident band is intact. Secondly, the device is confusing to theconsumer since the cap is screwed off during removal only by inwardlydistorting the cap skirt. The cap is reapplied as a standard snap cap.

Full thread engagement as the cap is initially applied has a number ofconceptual advantages. Consumer confusion is eliminated since initialremoval is by unscrewing. A number of seal systems, including foil, fullliner, plugs or other linerless seals can be used. However, fullengagement systems heretofore have been difficult to achieve inpractice. A disadvantage of a closure such as Carr U.S. Pat. No.4,625,875 is that there is no practical, consistent means to orient thecap relative to the container so that, after application, the cap mustbe turned at least slightly to ensure a tight seal. This defeats thepurpose of a push-on cap. Also, the use of a stretch snap-band tamperevident ring excessively increases the application force necessary toseat the cap.

The present invention provides full thread engagement by reason ofunique thread design and, more particularly, a unique tamper-evidentband (i.e., lower skirt portion) attached to the upper part of the capby multiple bridges or by means of a continuous line of weakness betweenthe cap and tear band, as well as a means of orienting closure andbottle threads to achieve registration prior to straight axialapplication.

The present invention has considerable advantages over prior structuresfor the reasons above noted, among others.

BRIEF SUMMARY OF THE INVENTION

The present invention comprises an improved closure or cap and animproved neck finish. The cap skirt and neck are provided with matingthreads of such shape that the cap may be applied in a simple downwardvertical movement, the cap skirt and neck flexing sufficiently to permitthe threads to slip past each other.

The threads may be continuous or interrupted. Also, instead of therebeing two threads—one on the neck and one on the cap, one externalthread may be replaced with a groove. The term “helical engagementmeans” is sometimes used herein to encompass all such screw retentionmeans.

The cap has a tamper-evident tear band below the skirt which isconnected to the skirt by a plurality of bridges or by a continuous lineof weakness. Ratchet teeth are positioned on the inside of the tamperevident band. Correspondingly, the container neck below the threads isformed with external ratchet teeth. The mating ratchet teeth of the capand container neck are engaged by the initial downward movement of thecap relative to the neck. In other words, in order to engage the ratchetteeth it is not necessary to rotate the cap relative to the neck,thereby differing from conventional threaded tamper-evident caps. It ismerely necessary to provide alignment means on the cap and on thecontainer so that the cap is initially properly oriented in suchposition that a direct single vertically downward movement of the caprelative to the neck causes the threads to slip relative to each otherand the ratchet teeth to lock in final position. Chamfers on the ratchetstructure of either closure or container can be used as a “fine”orientation system as the closure is initially applied.

To achieve proper registration of threads when a simple direct axialapplication force is used, both the neck threads and closure threadsmust be oriented. Orientation of the container is relatively easy.Generally, containers are either non-circular or have non-circularfeatures which may be used for proper orientation. In accordance with apreferred form of the invention shown herein, the closure has a downwardprojecting tab similar to the tear tab used on push-on tear-offclosures. The vertical tear tab characteristic of the present closure isan excellent orientation feature. However, other means for orienting thecap and container may be used.

Thread design is another feature of the invention. A large number ofthreads per inch of axial height is desirable for two reasons. First, afine thread may be used and such a thread does not have to be as deep asa coarse thread, and hence the forces required for threads to jumpduring application are minimized. Secondly, fine threads minimize theheight required to achieve a standard design criterion of 360° or moreof thread engagement which permits a lighter closure weight.

The greater the number of thread leads, the less actual turning actionis required to remove or reapply the cap. In addition, multiple threadleads promote more “squareness” during straight axial application. Inother words, the cap seats horizontally on the neck because the terminiof the threads are statically balanced. However, additional leadsrequire a higher thread pitch assuming constant threads per inch andexcessively high thread pitch results in a situation where the closuremay back off or unscrew itself from sealed position.

In accordance with the present invention, a preferred thread for ablow-molded, high density polyethylene bottle is 12 threads per inch andtwo leads. If bottle finish processing permits, it would be advantageousto design for higher threads per inch and more leads. For example, ifthe bottle is made with injection blow mold equipment, a very finebottle thread is possible. In that case, it might be preferable to use,for example, a 16 thread-per-inch, 4 lead, 4 pitch thread. The moreleads, the more squarely the cap sets on the neck and the moreeffectively the closure will be seated by a direct downward, axialapplication force.

Also, consumer advantages of quick release and reapplication can beachieved with multiple lead threads.

In order to provide a tamper-evident feature, the closure should not beremovable without some apparent closure characteristic changing.Generally, this requirement is satisfied by incorporating a frangiblesection which is destroyed during initial closure removal. One type offrangible section is a continuous thinned tear line, but in a cap of thepresent invention, such a system may not be the best choice, althoughpermissible and is disclosed as a modification of the first embodimentof the invention. A preferred tamper-evident feature provides afrangible section having a number of frangible connections or bridgesbetween the closure skirt and a tamper-evident ring below the bottomedge of the skirt. The preferred approach is to incorporate enoughbridges around the circumference such that the combined strength of thebridges prevents unscrewing. The tamper evident band must be removed toallow unscrewing. Sequential breaking of the many bridges around thecircumference simulates a continuous tear. A second approach is toincorporate only a few bridges around the circumference of the skirtsuch that the combined strength of the bridges is not sufficient toprevent unscrewing and the bridges rupture as the cap is initiallyunscrewed. With this second approach the broken bridges give evidence ofopening. A major advantage of using bridges rather than a continuoustear strip is that a wide range of material choices is possible.Therefore a multiple bridge simulated tear structure is generallypreferred over continuous tear frangible sections and this approach isused in the preferred embodiments of the present invention. However, ina modification of the invention an uninterrupted horizontal shoulderbetween the upper and lower portions of the cap is used, which shoulderis formed with a line of weakness. The alternative modificationeliminates the space between the bridges to create a continuousfrangible line. This modification is used successfully only when the capis formed of a low density polyethylene and is not successfully usedwith higher density plastic materials. One of the advantages of theelimination of the spaced bridges is that of cleanliness in that thecontinuous shoulder prevents dirt and liquids from contacting anyportion of the neck surface above the bottom edge of the cap.

In a preferred embodiment of the invention hereinafter described indetail, the closure is first oriented by means of its tear tab and thecontainers are likewise oriented. The closure and bottle are snappedtogether and the orientation allows registration of both the threads andthe ratchets which hold the cap in place until the tamper-evident bandis removed. Seal of the container may be made with a liner, foil or alinerless feature such as a plug or flap. Before initial removal, themultiple bridges are collectively sufficiently strong to preventunscrewing and also resist any tendency of the closure to back off theneck. During initial removal, in the preferred embodiment the tear bandis removed through sequential breaking of the bridges, therebysimulating a continuous tear strip but allowing the use of such plasticmaterials as polypropylene and high density polyethylene. Once the tearband is removed, the system functions as with normal threaded closures.Alternatively the upper and lower portions of the cap skirt areconnected by a reduced number of angularly spaced bridges. Merely bytwisting the upper skirt portion the bridges may be severed, givingevidence of tampering, and making it possible to unscrew the cap.

One of the features of the present invention is that the lower skirtportion, which includes tamper-evident features and, more particularly,contains ratchet teeth mating with corresponding teeth on the containerneck, is formed with a vertical line of weakness and a tear tab adjacentthereto. When the lower skirt is removed it tears along the verticalline of weakness as well as along the line of weakness between the upperpart of the cap and the lower skirt (i.e., tamper-evident band.) Thisfeature has a number of advantages:

First, it prevents defeating the tamper-evident feature. Were it not forthe vertical line of weakness, a dishonest patron might unscrew theupper cap, remove the contents of the container and replace the cap. Itis somewhat difficult to observe that the line of weakness between theupper cap and tamper-evident band has been severed. When the verticalline of weakness is severed, this is not a problem since the lower skirtcannot be replaced.

Second, if the molds for the cap are not perfectly supported, plasticmaterial may fill some or all of the voids between bridges joining theupper cap to the tamper-evident band. This makes it difficult for someusers to remove the tamper-evident band. The vertical line of weaknessmakes it much easier to remove the lower skirt or band. Indeed, thebridges between the upper cap and band may be made thicker or some ofthe voids between bridges may be eliminated.

Thirdly, the intact tamper-evident band may create a danger to wildlifeif the head of a bird, fish or small animal is entrapped therein.Splitting the band along the vertical line of weakness eliminates thishazard.

A further feature of the invention is the fact that the cap ratchet lugon the interior of the lower cap skirt is located between two externallugs on the neck finish when the cap is applied so that on applicationthe cap cannot rotate outside of its “tolerance range”, that is, thereis an orientation feature of the cap and bottle ratchets for properengagement.

Another advantage of the invention is that the cap may be applied to theneck in two stages (i.e., “double click”). When the container is filledwith milk or certain other liquids, entrapped air or other gases tend tocause foam. The thread structure of the present invention makes itpossible to press the cap down until one set of threads passes theother. This holds the cap on the neck and holds it properly alignedrelative to the neck ratchet. However, the cap is not tight and henceair and gas may escape. Then the cap is pressed down once more totightly engaged and sealed position. To insure two “clicks” the closurethread has to jump two neck threads during application. This means thatif the cap threads extend a full 360° around the cap skirt inner wall(180° each for double lead threads), the finish threads have to berepetitive at some point of the circumference. This also means thateither the cap threads or the finish thread must be repetitivevertically. I.e., the threads must overlap on either the neck or cap inorder to make possible the double click.

More specifically, the caps pass down a conveyor overlying the path ofthe containers and as each container passes the end of the conveyor, acap drops onto the neck. The cap and neck then pass under a roller whichpreliminarily presses the cap down on the neck. One of the features ofthe thread construction of the present invention is that there is morethan one full turn of thread engagement of the threads. Hence, theroller pushing the cap through the first step or snap prevents thelatter from falling off the neck when it is subjected to such action asmilk foaming in the interior of the container. Hence the cap stays onthe bottle, although not being tightly sealed thereto, until the bottlepasses under the conventional capping machine belt or pressure platewhich fully seats the cap on the neck. This is a second step or snap ofthe cap on the bottle and insures that both threads are tightly engaged.

When the first snap of the cap on the bottle occurs, the ratchet teethof the cap engage the ratchet teeth of the neck but a slight twisting ispossible within the range of tolerance of approximately 20°. Such arotation of the cap relative to the neck changes the height of the caponly about 0.009 inches. However, this turning ability of the caprelative to the neck with such slight changes in the height of the caprelative to the neck insures proper final alignment of the ratchet teethof the cap and neck, while permitting release of foam or excess air.

Still another feature of the invention is an internal shoulder at theintersection of the underside of the disk and the top of the upper capskirt. This shoulder prevents the cap from being turned or torqued tojump threads or strip the threads. The inner plug of the cap tends topush the neck of the bottle outward against the shoulder and theshoulder then prevents turning or stripping. Further, the fit of theshoulder against the neck tends to reduce leakage and rigidifies thecap.

Another feature of the present invention is that the cap is providedwith a plug or inner skirt which fits inside the bottle neck. The lengthof this plug is related to the positioning of the screw threads on thecap in such manner that the threads of the cap and bottle neck engagebefore the plug engages the neck. Thus a quarter-turn of each of thedouble lead threads occurs before the plug contacts the neck. Thisfeature reduces the possibility of cross-threading when the cap isapplied to the neck as a reclosure cap.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part ofthis specification, illustrate embodiments of the invention and,together with the description, serve to explain the principles of theinvention:

FIG. 1 is a side elevational view of a cap and neck before assembly, thecap being partially broken away in section to reveal internalconstruction.

FIG. 2 is a bottom plan of the cap.

FIG. 3 is a fragmentary enlarged top plan of the cap.

FIGS. 4 and 5 are, respectively, enlarged, fragmentary sectional viewstaken along lines 4-4 and 5-5 of FIG. 2.

FIG. 6 is a top plan of the neck.

FIGS. 7 and 8 are, respectively, enlarged fragmentary sectional viewstaken along lines 7-7 and 8-8 of

FIG. 9 is an enlarged, fragmentary sectional view through an assembledcap and neck taken in the positions of line 4-4 of FIGS. 2 and 7-7 ofFIG. 6.

FIG. 10 is a view similar to FIG. 9 taken in the positions of line 5-5of FIGS. 2 and 8-8 of FIG. 6.

FIG. 10A is a view similar to FIG. 10 of a modification.

FIGS. 11A, 11B and 11C are schematic views showing progressive “doubleclick” cap attachment wherein the cap thread has one turn and the neckhas multiple threads.

FIGS. 12A, 12B and 12C are views similar to FIGS. 11A, 11B and 11Cwherein the neck thread has on turn and the cap thread multiple turns.

FIG. 13 is a bottom plan view of a cap.

FIG. 14 is an enlarged, fragmentary sectional view of a cap taken alongline 14-14 of FIG. 13.

FIG. 15 is an enlarged, fragmentary sectional view of a cap taken alongline 15-15 of FIG. 13.

FIG. 16 is an enlarged, fragmentary sectional view taken along line16-16 of FIG. 15.

FIG. 17 is an enlarged, fragmentary sectional view of a cap applied to aneck.

FIG. 17A is an enlarged, fragmentary sectional view of a cap applied toa neck.

FIG. 18 is a fragmentary, top plan view of a container.

FIG. 19 is a fragmentary, bottom plan view of an another embodiment of acap.

FIG. 20 is an enlarged, fragmentary sectional view taken along line20-20 of FIG. 19.

FIG. 21 is an enlarged, fragmentary side elevational view of analternative embodiment of a cap, shown partly in cross section.

FIG. 22 is an enlarged, fragmentary side elevational view of analternative embodiment of a neck.

FIG. 23 is a fragmentary, top plan view showing the cap applied to acontainer.

FIG. 24 is an enlarged, fragmentary side elevational view of anotherembodiment of a cap.

FIG. 25 is a top plan view of a cap applied to a container.

FIG. 26 is a fragmentary plan view of a capping machine, showing a cappositioned within the chute.

FIG. 27 is a partial top plan view of a capping machine, showing acontainer positioned on the conveyor belt.

FIG. 28 is a side elevational view of another embodiment of a neck.

FIG. 29 is a top plan view of the neck of FIG. 28.

FIG. 30 is an enlarged, fragmentary sectional view taken along line30-30 of FIG. 29.

FIG. 31 is a bottom plan view of another embodiment of a cap.

FIG. 32 is an enlarged, fragmentary sectional view taken along line32-32 of FIG. 19.

FIG. 33 is view similar to FIG. 32 of another embodiment of a cap.

FIG. 34 is a perspective view of a cap showing possible upwarddeformation of the lower skirt portion to the cap.

FIG. 35 is a side elevational view of a cap and neck before assembly,the cap being partially broken away in section to reveal internalconstruction.

FIG. 36 is a fragmentary enlarged bottom plan of the cap.

FIG. 37 is a fragmentary enlarged top plan of the cap.

FIG. 38 is an enlarged, fragmentary sectional view taken along line38-38 of FIG. 37.

FIG. 39 is an enlarged, fragmentary sectional views taken along line39-39 of FIG. 37.

FIG. 40 is an enlarged, fragmentary sectional view taken along line40-40 of FIG. 35, showing a preferred cross-sectional shape of a line ofweakness.

FIG. 41 is a fragmentary enlarged top plan of an alternative embodimentof a cap of the present invention.

FIG. 42 is an enlarged, fragmentary sectional view taken along line42-42 of FIG. 41.

FIG. 43 is an enlarged top view of another alternative embodiment of acap of the present invention.

FIG. 44 is a side elevational view of the cap of FIG. 43.

FIG. 45 is a fragmentary sectional view taken along line 45-45 of FIG.43.

FIG. 46 is perspective view of another cap of the present invention.

FIG. 47 is a sectional view of the cap of FIG. 46 mounted on a containerneck taken substantially along line 47-47.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings. While the invention will be described in conjunction with thepreferred embodiments, it will be understood that they are not intendedto limit the invention to those embodiments. On the contrary, theinvention is intended to cover alternatives, modifications andequivalents, which may be included within the spirit and scope of theinvention as defined by the appended claims.

Cap 21, hereinafter described in detail, is used with a container neck22. Neck 22 has a central neck opening 23 and extending outwardlythereof a downward-outward slanted lip flange 24 which terminates in avertical stretch 28. The exterior of neck 22 is hereinafter described.The interior thereof forms no part of the present invention. With ablow-molded bottle finish as illustrated in FIGS. 7 and 8, the interiorcontour of the neck generally tends to follow that of the exterior.However, it will be understood that other types of bottles may be usedand in such instances the internal neck shape may vary from that of theexterior.

Extending outward of stretch 28 are threads 29. In the depictedembodiment of FIGS. 7 and 8 there are two threads 29 designated 29 a and29 b. In the embodiment, the finish has twelve threads per inch with adouble lead, each thread being six pitch and extending slightly inexcess of 360° of a full thread. Thus the upper terminus 31 of the firstthread is vertically displaced approximately 0.166 inch from the lowerterminus 32 thereof. The upper terminus 33 of the second thread isdisplaced 180° relative to terminus 31 and its lower terminus 34 isapproximately diametrically opposite terminus 32. It is understood thatthe threads can be extended greater than 360° to achieve increasedthread engagement. Also, additional thread leads and different linearthread density (threads per inch) are permitted and may beadvantageously chosen. In order to permit the threads of the cap to slippast the threads of the neck, as shown in FIG. 7, the upper flank 36 ofthread 29 slants downwardly and outwardly at approximately 45° while thelower flank 37 slants downwardly and inwardly at an angle of about 10°.Preferably the thread apex 38 is made with as large a radius aspossible. A portion 41 of vertical stretch 28 is located below thethreads 29 extending down to upper shoulder 42, which is horizontal.

As stated previously, instead of threads on the inside of the skirt andoutside of the neck, one thread may be replaced by a groove. Further,instead of threads 29 being continuous, they may be interrupted.

Below shoulder 42 is locking area wall 46 which slants downward/outwardat an angle of about 10°. Wall 46 terminates in lower shoulder 47 whichis also approximately horizontal. Outwardly of and below shoulder 47 isa lower vertical stretch 48 which at its lower end merges with thecontainer. Bumper ring segments 49 (here shown as four in number) may beformed in the stretch 48 to facilitate gripping the container duringfilling and loading and also to provide certain vertical flexibility tothe neck during the capping operation.

On opposite sides of neck 22 projecting out from wall 46 are teeth 51.As illustrated in FIG. 6, there are typically three such teeth on oneside of the container neck and three teeth on the opposite side. Thetotal extent of the three teeth on each side is approximately 90°. Eachtooth has a top surface 52 which can be co-planar with the surface ofshoulder 42. Outer surface 53 slants downward/outward at an angle ofapproximately 10°, terminating in shoulder 47. The front edges 54 viewedfrom above in plan as in FIG. 6 (assuming a right-hand thread) aredisposed at varying angles from about 45° to about 0° relative to aradial line drawn perpendicular to the vertical axis and areapproximately vertical.

A preferred cap 21 used with the neck structure 22 previously describedis illustrated in FIGS. 1 to 5. The cap has a generally flat top disk 61from the periphery of which depends substantially vertical short upperskirt 62. The lower edge of skirt 62 merges with slanted stretch 63,which, in turn, merges with vertical stretch 64. An internal shoulder 65is formed at the intersection of stretches 62 and 63. Members 62, 63, 64have vertical ribs 66 spaced therearound to enable the user to grip thecap. Chamfers 67 are preferably formed on the upper edges of ribs 66.The ribs of the cap are thus, in effect, rounded but extend higher.Hence they are more severely gripped by the user when screwing orunscrewing the cap.

On the interior of skirt 66 are formed threads 71 a and 71 b which areselected to mate with threads 29 a and 29 b of neck 22. The bottom edge72 of skirt 64 is connected to shoulder 73 and generallydownwardly/outwardly slanted lower skirt 74 by a plurality of bridges 76which in fact constitute the lower edges of ribs 66. The bridges andvoids therebetween are sometimes referred to herein as “horizontal linesof weakness”. Skirt 74 has a generally horizontal lower edge 77.

Teeth 81 spaced and dimensioned to match the teeth 51 of neck 22 areformed on the inside of wall 74. The inner edges 82 of the teeth arepositioned close to inner surface 46 after cap application. The leadingedge 83 of each tooth 81 is formed at an angle of approximately 45° to aradial line, thereby ensuring good interlock with the complementarysurface 54 of neck 22. This angular relationship biases the cap 21 intoa more secure locking arrangement with the neck 22.

Tear tab 86 extends downwardly from lower edge 77 and an upper side edgethereof merges with a weakened vertically extending line 87 formed inskirt 74. Use of weakened line 87 is optional, but preferably used toprevent the ring-like skirt 74 being a hazard to wildlife and toaccomplish the other objects set forth earlier in this description. Whenthe consumer grips tab 86, bridges 76 are severed and the verticalweakened line 87 is broken. Thus pulling the tab 86 sequentiallyfractures weakened line 87 and then each of the bridges 76 (i.e., thehorizontal weakened line). Removal of the lower skirt 74 removes theratchet teeth 81 and hence frees the upper portion of the cap so that itcan be unscrewed. However, such removal of the lower skirt givesevidence of the opening of the cap and hence is a tamper-evidentfeature. Alternatively, the user may twist upper skirt 64, severingbridges 76. To prevent defeating the tamper-evident features of the cap,the bridges may be made stronger. A combination of circumferentiallyspaced thin bridges 76 and arcuate continuous areas relieved by circulararc tear lines may be used.

Although various liners may be used to secure the under side of disk 61to the lip flange 24 of neck 22, in the accompanying drawings, apreferred embodiment shows an inner skirt or plug 91 extending downwardfrom top disk 61 and fitting inside the neck opening 23. Preferably theouter bottom edge of skirt 91 is formed with a bevel 92 to facilitateseating of the cap 21 on the neck 22. A circular rib 94 on the undersideof disk 61 is located between plug 91 and skirt 62 and engages neck lipflange 24 to provide a secondary seal.

The threads 71 a, 71 b of cap 21 are double lead and each extends aroundthe circumference of the cap in excess of 180°, i.e., approximately200°. The threads 71 a, 71 b originate very close to the bottom edge 72of vertical stretch 64. Threads 29 a and 29 b of the neck 22 originatespaced somewhat downwardly from the top on vertical stretch 28. As haspreviously been stated in the summary of this invention, in conventionalcapping machines, cap 21 is deposited on neck 22. Because of the factthat the threads 71 b and 71 a are diametrically opposed, the cap 21tends to rest on the neck 22 approximately horizontally. The first stepin seating cap 21 is to pass under a roller which pushes the cap 21downwardly. The threads on the cap slip over the uppermost threads onthe neck 22 during this first step which may be termed a “first snap”.At this point the cap is not fully seated, still resting at least onebottle thread above its fully seated and applied position. If thecontainer has been filled with a substance such as milk which tends tofoam, the first snap action permits some of the air in the container toescape since the cap is not completely sealed on the neck. Thereafter,the cap and container pass under a seating belt or pressure plate whichforces the cap 21 downward until it is completely seated on the neck 22,thereby completing the second snap or step. To achieve this advantageous“double snap application” the relative axial movement of cap and bottleneck to a fully sealed and seated position must involve a portion of thecap threads jumping at least two neck threads or vice versa.

The first step in the seating of the cap on the neck (first snap) bringsthe teeth 81 of the cap into partial engagement with the teeth 51 of theneck, but within about a 20° tolerance. This permits the aforementionedfoaming without allowing cap rotation away from proper orientation. Thesecond step of the seating causes the teeth 81 and 51 to fullyinterengage.

Another feature of the invention best shown in FIG. 9 is the function ofthe shoulder 65 of cap 21. The inner plug 91 tends to push the lip 24outwardly. Hence the shoulder 65 tightly engages the surface 28 andpromotes effective sealing.

Directing attention now to FIG. 10A, instead of bridges 76 being formedconnecting the shoulder 73 a to the lower end of vertical stretch 64 a,the shoulder 73 a is continued inward but the material is very thin. Inother words, a horizontal line of weakness 97 replaces the bridges 76but the line of weakness is continuous. Hence the lower skirt 74 a maybe removed by tearing away the line of weakness 97.

The use of the modification of FIG. 10A is particularly suited when thecap is made of a material such as low density polyethylene. An advantageof having a line of weakness rather than separated bridges is that dirtand water cannot enter in the voids between the bridges and collectbetween the cap and neck.

In other respects the modification of FIG. 10A resembles that of thepreceding modification and the same reference numeral followed by thesubscript a is used to designate corresponding elements.

Preferred Operation I

After the container has been filled, it is transported through a cappingmachine. As is well understood in the bottling art, and in a mannersimilar to that whereby push-on, pull-off caps are applied, the caps 21are fed one at a time out of a bowl in the capping machine along aconveyor, the tear tabs 86 orienting the caps so that they are alldischarged in a pre-determined orientation relative to the containerswhich pass therebelow. Although not shown in the accompanying drawings,each container has a square cross-section or some other variation from around shape which permits the container neck 22 to be oriented relativeto the cap 21. The structure of capping machines is well known in thebottling art. Because of the relative orientation of the cap 21 andcontainer neck 22, the teeth 81 of the cap are in vertical alignmentwith the gaps between teeth 51 of neck 22. An axially downward force isapplied to cap 21 causing it to move down. As it moves down, the innerskirt 91 fits inside neck opening 23. The threads 71 a and 71 b slipover the threads 29 a and 29 b, the slanted surfaces 36 facilitatingsuch movement. As has been stated, the sealing is preferably in twosteps or snap actions. The cap 21 is sufficiently resilient so that itexpands outward sufficiently to permit the threads to slip. As the cap21 seats on the neck 22, the teeth 81 engage between the teeth 51 tofully seat the teeth 81 in place. Flange 24 then engages the under sideof disk 61 and the outer wall of inner skirt 91, sealing the container.The engagement of threads 71 and 29 retain the cap tightly to the neck.

FIGS. 11A, 11B and 11C illustrate schematically the two-step seatingheretofore described. In FIG. 11A the single turn cap thread 71 b restson the top of the uppermost neck thread. In FIG. 11B the thread 71 b ofthe cap has been pushed over neck thread 29 a but the cap is not fullyseated. Hence gases may escape from the container. In FIG. 11C thesecond click occurs, when thread 71 b seats under thread 29 b.

FIG. 12A shows a reverse situation wherein thread 29 a on the neck restsunder the cap thread 71 b. In FIG. 12B the first click has occurred andthread 29 a is between threads 71 a and 71 b. FIG. 12C shows completionof seating wherein thread 29 a is above threads 71 a and 71 b.

After the cap 21 has been fully seated on neck 22 it cannot be removedwithout giving evidence of tampering. Thus the interengagement of teeth81 and 51 prevent unscrewing the cap and the interengagement of threads71 with threads 29 prevents lifting the cap off the neck.

When it is desired to open the container, the user grips the tab 86 andbreaks line 87, then pulls circumferentially around the containercausing the lower skirt 74 to be removed, thereby removing the teeth 81.This gives evidence of tampering. However, it also permits the user togrip the ribs 66 and unscrew the cap 21 from neck 22.

To replace the cap, it is merely necessary to reverse the direction ofturning. Directing attention now to the structure shown in FIG. 1,another feature of the relationship between the plug 91 and threads 71a, 71 b is shown. It is desirable that when the portion of the cap 21above the lower skirt 74 is used as a reclosure cap, that proper seatingof the reclosure cap be insured so that the reclosed bottle does notleak. In FIG. 1 the reference letter X is used to designate the verticaldistance between the upper edge of threads 71 a and 71 b and the pointat which the flange 24 of neck 22 contacts the slanted surface 92 ofplug 91. The reference letter Y is used to designate the minimumvertical dimension between the top edge of vertical stretch 28 of neck22 and the underside of the thread start 31. A feature of the structureis that at some position of the cap the dimension X be greater than thedimension Y. Hence when the reclosure cap is placed on the containerneck, the threads interengage, preferably a quarter-turn or more beforethe upper edge of the container neck engages the inner skirt or plug.This prevents cross-threading or stripping of the threads when thereclosure cap is tightened on the neck.

As used in the claims, the term “thread” is used not only to includeexternal threads but internal ones as well and to include continuous andinterrupted threads or other “helical engagement means”. In thespecification and claims, the cumulative turn total for multi-leadthreads or other such helical engagement means is the sum total of thenumber of turns of the individual multi-lead threads around either theneck stretch portion or the upper skirt portion. For multi-lead threads,“in excess of one turn total” means that the sum total of the number ofturns of the individual threads is in excess of 360°. The language “atleast one vertically extending arc stretch” refers to a portion of theupper skirt or neck stretch where the threads overlap or are repetitivevertically, whereby a vertical line drawn within the arc stretch willintersect at least two threads. When the threads on either the cap orthe neck overlap (i.e. a vertical line drawn within the arc stretch willtraverse the helical engagement means at least two times), theapplication of the cap onto the container with at least two “clicks” isensured.

Closure 121, hereinafter described in detail, is used with a containerneck 122. The interior of the neck forms no part of the presentinvention. With a blow-molded bottle finish, the interior contour tendsto follow that of the neck exterior. However, it will be understood thatother types of bottles may be used, with the internal shape of the neckvarying from that of the exterior.

Neck 122 has a central opening 123 and a downward-outward slanted lipflange 124 terminating in an upper neck stretch 128. Threads 129 extendoutward of stretch 128. In the illustrated embodiment, there are twothreads 129 a and 129 b. The finish has twelve threads per inch with adouble lead, each thread being six pitch and extending slightly inexcess of 360° of a full thread. It is to be understood that the threadsmay be extended greater than 360° for increased thread engagement.Additionally, the thread leads may be of a different linear threaddensity (threads per inch). The upper flank 136 of thread 129 slantsdownwardly/outwardly at approximately 45° while the lower flank 137slants downwardly/inwardly at approximately 10°, permitting the threadson the interior of the cap to slip past the threads on the neck finish.Preferably, the thread apex 138 is made with as large a radius aspossible, but being sufficient to insure that the cap must be unscrewedand not pulled from the neck.

Instead of cooperatively shaped threads on the upper neck stretch andthe inner surface of the closure, one thread may be replaced by agroove. Further, threads 129 may be interrupted, instead of beingcontinuous.

The container neck includes a tamper-evidencing portion 40 below theupper neck stretch 128 which includes an outward extending shoulder 142,a locking wall 146 offset outwardly relative to the upper neck stretch128, and a lower outward extending shoulder 147. A plurality of upwardprojecting teeth 151 are formed on the tamper-evidencing portion of theneck. A vertical stretch 148 depends from shoulder 147. To facilitategripping the container during filling and loading, vertical stretch 148may be formed with a number of bumper ring segments 149 (here shown asfour in number).

The teeth 151 extend upwardly from the shoulder stretch 147. The teethare shaped and positioned to cooperate with internal teeth formed on theclosure, the interengagement between the teeth resisting unscrewing ofthe cap from the neck. Typically, multiple teeth 151 (FIG. 18) areformed on either side of neck 122, with the total extent of the multipleteeth being approximately 90°.

A cap for use with neck structure 122 is illustrated in FIGS. 13 to 17.The cap has a top 160 from the periphery of which depends downwardextending upper skirt 161. As illustrated, the top comprises a generallyflat top disk; however, other configurations may be substituted. Theupper skirt 161 is formed with a generally vertical upper edge 162 whichmerges with outward-downward slanted stretch 163, which in turn mergeswith vertical stretch 164. An internal shoulder 165 is formed at theintersection of stretches 162 and 163. A sealing bead 168 depends fromthe underside of top 160. When the cap 121 seats on the neck, bead 168engages lip flange 124, internal shoulder 165 engages the upper edge ofvertical stretch 128 and inner skirt or plug 191 engages lip flange 124,substantially sealing the container. Members 162, 163 and 164 haveradially spaced vertical ribs 166 to enable the user to grip the cap.

As is shown in FIG. 17A, the internal shoulder 165 provides an inwardprojecting portion 161 a of the upper skirt 161 which cooperates withthe exterior of the neck stretch 128. Since the circumference of theupper portion 128 a of neck stretch 128 is greater than the interiorcircumference of the cap 121 at the inward projecting portion 161 a ofthe skirt, a tight fit is formed between the inward projecting portionand the neck stretch exterior. The tight fit between the upper skirtportion above thread 171 a and the exterior of the neck stretch 128above thread 129 a promotes an effective seal between the exterior ofthe plug 191 and the interior edge 124 a of the lip 124. When the cap121 is applied to the neck 122, the upper skirt 161 is biased outward asthe inward projecting portion 161 a engages the exterior of the neckstretch 128. Since the closure is resilient, the inner plug 191 of thecap is urged toward the lip 124 to form a seal between the generallyseamless interior edge 124 a of the lip and exterior of the plug 191. Inother words, the inward projecting portion provides a means for biasingthe upper skirt and the plug outward to urge the plug into sealingengagement with the lip 124. The fit of the shoulder against the necktends to reduce leakage and rigidify the cap, preventing the cap frombeing turned or torqued to jump threads or strip the threads. The innerplug 191 of the cap 121 tends to push the neck of the bottle outwardagainst the shoulder and the shoulder then prevents turning orstripping.

Threads 171 a and 171 b, which are selected to mate with threads 129 ofneck 122, are formed on the interior of the skirt. The shape of threads129 a, 129 b, 171 a, and 171 b allow the threads to slip past oneanother and then interengage. In the presently described embodiment,threads 171 a and 171 b are double lead and each extend around thecircumference of the cap in excess of 180°, for example, approximately200°. In conventional capping machines, cap 121 is deposited on neck122. Since threads 171 a, 171 b are diametrically opposed, the cap tendsto rest horizontally on neck 122, facilitating the application of thecap onto the neck with a downward, axial force.

In order for the closure and container threads to effectively slip pasteach other during direct axial application it is necessary that thethreads be finer than would be appropriate for a threaded closureapplied by conventional rotary application. As threads become finer, agreater amount of total thread engagement is often necessary to preventexcessive forward stripping on reapplication. For the presentembodiment, which includes a linear density of twelve threads per inchand is formed with double leads, a thread engagement of approximately200° for each of the two cap threads is satisfactory (i.e. 400° of totalthread engagement). Finer threads such as sixteen or twenty threads perinch would require greater total thread engagement.

The closure includes a tamper-evidencing band 170 below the upper skirtportion 161 provided with a plurality of internal ratchet teeth 181. Inthe present embodiment, the tamper-evidencing band 170 comprises anannular shoulder 173 below the upper skirt 161 and an outer skirtportion 174 extending downwardly from the shoulder 173. The band 170 isjoined to the upper skirt 161 by a frangible section which allows theband 170 to be at least partially torn from the cap. The frangiblesection includes a number of radially spaced bridges 176 interconnectingthe shoulder 173 and the upper skirt portion, the bridges being providedby the lower edges of ribs 166. Alternatively, the frangible section maybe provided by a line of weakness formed along the intersection ofshoulder 173 and upper skirt 161. In the illustrated embodiment, theshoulder 173 and outer skirt portion 174 divide the band into twosections, with the outer skirt portion being oriented at an anglerelative to the annular shoulder. In a modified embodiment, discussed inrelation to FIG. 24, the tamper-evidencing band may comprise a single,curved section which extends generally outward and downward from theupper skirt portion. The tamper-evidencing band may also take many otherforms.

The tamper-evidencing band includes a plurality of the internal ratchetteeth 181 depending from the shoulder 173. The generally downwardlydepending teeth 181 are positioned to engage teeth 151 when cap 121 ispushed onto neck 122. Teeth 181 include an inclined surface 183 forfacilitating the application of the cap to neck 122 and a workingsurface 184 which cooperates with the working surface of one of theteeth 151 on the neck to resist unscrewing of the closure. As theclosure is moved downwardly on the neck, the inclined surface 183 slidesalong tooth 151 to thereby guide tooth 181 to a position betweenadjacent ones of teeth 151. The downward depending tooth 181 is retainedbetween the teeth 151, with the interengagement between the teeth 151and 181 securing cap 121 on the neck so long as the tamper-evidencingband 170 is intact. Teeth 181 are located on the shoulder in the presentembodiment; however, the teeth may alternatively be positioned at otherlocations on the tamper-evidencing band 170, such as along the innersurface of outer skirt portion 174.

The interlocking engagement between the teeth on the cap with those onthe neck prevents twisting of the cap relative to the container whilethe tamper-evidencing band 170 is intact. To remove the closure from theneck, the band 170 is at least partially removed from the upper skirt161 to disengage teeth 181 from the teeth 151 on the neck. Theseparation of the tamper-evidencing band 170 from the upper skirt 161 isaccomplished by rupturing the bridges 176. The ruptured bridges warn theconsumer that the container has been opened and the contents tamperedwith.

A tear tab 186 is connected to the lower edge of the tamper-evidencingband 170. In the present embodiment, the tear tab provides means forremoving the lower band and may additionally be used to orient cap 121relative to the container prior to application if desired. Thetamper-evidencing band 170 is formed with a line of weakness adjacenttab 186, generally indicated by 187, extending through outer skirtportion 174 and shoulder 173 of the band. The line of weaknessfacilitates removal of the band 170 from the closure, and is anothertamper-evidencing feature of the present invention. When initiallyopening the container, the consumer pulls tab 186 to remove lower band170, rupturing line 187 and frangible section 176. The absence of theband 170 more dramatically alerts the consumer to possible tamperingwith the contents. An inattentive consumer may fail to notice thefractured bridges, therefore the removal of the tamper-evidencing bandis a more obvious indication of tampering. In the preferred form,completely removing lower band 170 from upper skirt 161 aestheticallyenhances the appearance of cap 121, which is used to reseal thecontainer. However, in other forms of the present invention the lowerband may be only partially removed from the upper skirt portion forseparating teeth 151 from teeth 181 to unscrew the cap from thecontainer.

When a consumer desires to initially open the container, he grips tab186 and pulls circumferentially around the container detaching lowerband 170 from upper skirt 161. Ratchet teeth 181 are thereby removedfrom interlocking engagement with upward projecting teeth 151, enablingthe consumer to unscrew cap 121 from neck 122 and providing evidencethat the container has been opened. To replace the cap, the consumermerely reverses the direction of twisting.

A modification of the cap is shown in FIGS. 19 and 20. The modified cap121 c may be applied to a container having a neck configuration similarto that shown in FIG. 18. The cap 121 c includes a tamper-evidencingband 170 c which includes a number of downward depending teeth 181 c.The shoulder 173 c of the band extends horizontally outward from thelower edge of upper skirt portion 161 c, and the outer skirt portion 174c depends from the shoulder. A frangible section composed of a pluralityof circumferentially spaced bridges 176 c connects shoulder 173 c to thelower edge of upper skirt 161 c. The teeth 181 c are dimensioned andpositioned to engage the upwardly extending teeth 151 formed on theneck. To facilitate application of cap 121 c, teeth 181 c include abeveled inner surface 183 c. When pushing the closure onto the neck,inner surface 183 c directs the teeth 181 c into interengagement withteeth 151. The working surface 184 c engages the working surface of oneof the teeth 151 on the neck to resist unscrewing of the cap 121 c fromthe neck.

Teeth 181 c and teeth 151 cooperate to restrain unscrewing of cap 121 crelative to the neck while the lower skirt remains intact. To unscrewthe cap, lower band 170 c is removed from upper skirt portion 161 c byrupturing frangible bridges 176 c. The modified cap may include a teartab and a line of weakness extending through the lower skirt, asdescribed with reference to the previously discussed embodiment forfacilitating removal of tamper-evidencing band 170 c. Alternatively, cap121 c may be twisted, fracturing the bridges, and unscrewed from thecontainer with lower band 170 c remaining around neck 122. The use of atear tab and line of weakness is preferred, as it provides a clearer andmore obvious indication of tampering, facilitates recycling of thecontainer and substantially eliminates risk of injury to wildlife.

An alternative modification of the cap 121 d and neck 122 d of thepresent invention is shown in FIGS. 21 to 23. Neck 122 d is formed withseveral teeth 151 d circumferentially spaced along shoulder stretch 147d. A pair of adjacent teeth 151 d are separated by a space, generallydesignated 152, formed for receiving the teeth of the closure. When theclosure is applied to the neck, a tooth formed on the closure ispositioned within space 152 between the adjacent teeth 151 d, therebypreventing rotation of the closure relative to the neck.

Cap 121 d (FIG. 21) includes a domed top 160 d having an inner skirt 191d depending from the underside of the domed top. Inner skirt 191 dengages lip flange 124 d when the cap seats on the neck, forming aninternal seal between the cap and the neck. In this embodiment, thelower band portion 170 d comprises a number of teeth 181 d generallydepending from lower edge 68 of upper skirt 61 d. The tamper-evidencingmeans are provided by the teeth 181 d. The teeth 181 d are shaped andpositioned for interengaging teeth 151 d, with one tooth 181 d slippinginto space 52 as the cap 121 d is applied to neck 122 d. The teeth 181 dhave an inclined surface 83 d which slides along the tooth 151 d toposition the tooth 181 d in the space 52. The working surface 84 d ofthe tooth engages the tooth 151 d on the neck to resist unscrewing ofthe cap 121 d relative to the neck 122 d. The interengagement betweenteeth 151 d and teeth 181 d substantially restricts twisting of theclosure relative to the neck, preventing unscrewing of the cap with thetamper-evidencing structure intact.

To remove cap 121 d from neck 122 d, the band 170 d, which is formedwith the downward depending teeth 181 d, must be severed from upperskirt portion 161 d. As is shown in FIG. 21, a line of weakness 179extends about the circumference of the closure between the upper skirtportion 161 d and the band 170 d. To open the container for the firsttime, the band 170 d is torn away at the line of weakness, facilitatingunscrewing of the closure. Removal of the band 170 d is facilitated by atear tab which is gripped while initiating a continuing tearing away ofthe lower skirt portion. As is shown in FIG. 23, one of the downwardextending teeth 181 d may be extended to provide a tear tab. When thecap is applied to the neck, the tear tab is deformed outward bydepressed section 143 of shoulder stretch 147 d. The consumer grips thetear tab shown in FIG. 23 and removes the lower band portion 170 d toseparate the interengaged teeth 151 d and 181 d and open the container.

Another modification of a cap 121 e of the present invention is shown inFIG. 24. The cap 121 e may be used with a neck of the type shown in FIG.18. The cap 121 e includes an upper skirt 161 e having a generallyvertical portion 164 e and a lower band portion 170 e. The lower band170 e extends generally outward and downward from the lower edge ofvertical portion 164 e, and is formed with a curved section 180. Anumber of internal teeth 181 e are formed on the interior of the curvedsection 180 of the lower band. A frangible section, provided in thepresent embodiment by a line of weakness 176 e, joins the lower band 170e to the upper skirt portion 161 e. A tear tab 186 e depends from thelower band 170 e. When the cap 121 e is applied to the neck 122, threads171 e slip past and interengage threads 129. Curved section 180 slipsover outward extending shoulder 142 and lower neck portion 146, with theteeth 181 e being shaped and positioned to interengage teeth 151. Aswith the previously described modifications, to open the container theconsumer pulls tab 186 e, fractures the line of weakness 176 e andseparates the lower band from the upper skirt, disengaging teeth 181 efrom teeth 151.

Turning to FIG. 25, cap 121 is shown seated on container 125. With thepresent invention, the closure may be conveniently oriented relative tothe container prior to applying the closure to the neck. The tab 186 andthe non-circular cross section of the container are directed by thecapping machine during the capping process to align the cap andcontainer relative to one another, positioning teeth 151 and 181 fordirect interengagement when the cap is pushed onto the neck. However,the cap construction of the previous embodiments fosters substantialseating of the cap without prior orientation. For example, the lockingmeans of the closure and neck are cooperatively shaped to slip past oneanother, thereby guiding the teeth 181 formed on the closure intointerengagement with the teeth 151 formed on the neck. By firstorienting the cap, full thread engagement may be achieved once the capis pushed onto the neck. However, it is to be understood that in manyinstances, full thread engagement or complete interengagement of theteeth 151 and 181 is not necessary to securely retain the cap on thecontainer. The various features of the present invention are not to berestricted to a snap-on, screw-off closure system in which the cap andcontainer are first oriented relative to one another.

FIGS. 28-32 illustrate another embodiment of a neck 122 f and cap 121 fin accordance with the present invention. The neck 122 f includesmultiple threads 129 f on the upper neck stretch 128 f. As shown in FIG.29, the neck 122 f includes seven threads 129 f although it is to beunderstood that a greater number of threads may be employed if desired.In this embodiment, the thread finish has a linear thread density ofmore than 17 threads per inch, for example 17.5 threads per inch, andeach thread extends more than 200°, for example 215°, around thecircumference of the upper neck stretch 128 f. The thread density andlength of each thread are also subject to variation within the scope ofthis invention.

A plurality of teeth 151 f are formed on the locking wall 146 f of theneck 122 f. As shown particularly in FIG. 20, the teeth 151 f include aworking surface 154 and a trailing surface 155. The working surface 154engages the working surface of a tooth on the cap to resist unscrewingof the cap relative to the neck. The trailing surface 155 joins theouter edge of the working surface 154 of one tooth 151 f to the inneredge of the working surface 154 of the adjacent tooth as shown in FIG.29. In other modifications of the invention, the teeth 151 f may bespaced apart so that the trailing surface 155 ends at the locking wall146 f and is not joined to the adjacent tooth. The trailing edges 155allow the cap 121 f to be twisted slightly, usually no more than about50°, to fully seat the cap on the neck after the cap has beensubstantially applied by pushing the cap in an axial direction onto theneck.

As shown particularly in FIGS. 28 and 30, each tooth 151 f includes abevel 156 at the upper edge of the tooth 151 f. The bevels 156 slantdownwardly and outwardly to guide the cap teeth 181 f into side-by-sideinterengagement with the teeth 15 f. In the embodiment of FIGS. 28-30,the bevel 156 is inclined at an angle of about 40° to 50°, such as 45°,relative to a horizontal plane. However, a bevel of an angle in therange of 10° to 70° may be employed.

The cap 121 f is shown in FIGS. 31 and 32. The cap 121 f includesmultiple threads 171 f on the interior of the upper skirt 161 f whichmate with the multiple threads 129 f on the upper neck stretch 128 f. Inthe illustrated embodiment, the cap 121 f includes seven threads eachhaving a length of about 180°, and the thread finish has a linear threaddensity of more than 17 threads per inch, such as 17.5 threads per inch.As with threads 129 f, it is to be understood that the number ofthreads, the length of the individual threads, and the linear threaddensity is subject to considerable variation within the scope of thepresent invention.

A plurality of teeth 181 fare provided on the interior of thetamper-evidencing band 170 f. In the illustrated embodiment, teeth 181 fare formed around the entire circumference of the band 170 f, however inother embodiments the teeth 181 f may be arranged in groups spacedaround the interior of the band 170 f. The teeth 181 f have a workingsurface 184 f and a trailing surface 185. The working surface 184 fcooperates with the working surface 154 of the teeth 151 f on the neckto resist unscrewing of the cap 121 f from the neck 122 f, while thetrailing surface 185 joins the outer edge of the working surface 184 fto either the inner edge of the working surface 184 f of an adjacenttooth or ends at the inner wall of the band 170 f. When the cap 121 f ismoved downwardly onto the neck 122 f in an axial direction, the loweredge of some of the teeth 181 f contact the bevel 156 on the teeth 151f, which guides the teeth 181 f into side-by-side engagement with theteeth 151 f.

In this embodiment shown in FIGS. 31 and 32, the downward slope of theworking surface 184 f and the trailing surface 185 follows the slope ofthe band 170 f. In this instance, both the band 170 f and the surfaces184 f and 185 are substantially vertical corresponding to thesubstantially vertical orientation of the locking wall 146 f. However,the band 170 f may also be slanted downwardly and outwardly as shown forexample by the band 170 in FIGS. 1-5. The bottom or lower edge of theteeth 181 f of the embodiment shown in FIGS. 31-32 is substantiallyhorizontal. When the neck 122 f is used with the cap 121 f, the bevels156 provide the primary means for guiding the teeth 151 f and the teeth181 f into interengagement. The neck 122 f may also be used with othercaps such as a cap 121 g shown in FIG. 33. The teeth 181 g of the cap121 g have a bevel or inclined surface 183 g which is slanted in adownward-outward direction. The bevel 183 g cooperates with the bevel156 to guide the teeth 151 f and 181 g into side-by-sideinterengagement. The neck 122 f may also be used with caps of the typeshown in FIGS. 13-18 and FIGS. 19-20, modified to include threadsmatching the thread pattern on the neck 121 f.

Except as set forth above, the modifications of FIGS. 19-20, 21-23, 24,28-32 and 33 resemble those of the preceding modifications and the samereference numerals followed by the subscripts c-g, respectively, areused to designate corresponding parts.

Preferred Operation II

After the container has been filled, it is transported through a cappingmachine. The structure of capping machines is well known in the bottlingart. As is well understood in the art, and in a manner similar to thatwhereby push-on, pull-off caps are applied, caps 121 are fed one at atime out of a bowl 111 in the capping machine along a chute 112 (FIG.26). One type of chute 112 is formed with a slot 113 between parallelrails 114, with tear tab 186 orienting the caps for uniform discharge ina pre-determined orientation relative to the containers passingtherebelow by fitting into the space 113 between the rails 114. Chuteswithout slots may be used when the tab does not depend from the loweredge of the tamper-evidencing band or when the cap is not orientedrelative to the neck before it is applied.

When orientation is employed, each container 125 preferably has anon-circular cross section or some other variation from a round shape,such as the rectangular shape shown in FIG. 25, which permits thecontainer to be oriented relative to cap 121. The container 125 travelsalong a conveyer belt 116 below the capping machine (FIG. 27). Guiderails 117 adjacent the conveyor belt 116 directionally align thenon-circular cross section of the container 125 relative to the tear tab186 of the cap. Using the slot 113 between the parallel rails 114 andthe guide rails 117, the cap 121 and neck 122 may be convenientlyoriented relative to one another by the conventional capping machine andconveyor belt system.

As is well known in the art, the container passes below the chute andpicks up a cap 121 such that the cap is resting on the neck 122. Iforientation is employed, the threads 129 and 181 are in verticalalignment, ensuring full thread engagement. Otherwise, the orientationof the cap relative to the neck is random. An axially downward force isapplied to the cap, pushing the cap onto the neck without externallyimposed relative rotation of the cap and container. Threads 171 a and171 b slip over threads 129 a and 129 b, the slanted surfaces 136facilitating such movement. The cap is sufficiently resilient so that itexpands outward to permit the threads to slip. As cap 121 seats on theneck, teeth 181 fall behind teeth 151, providing interengagement betweenteeth 151 and teeth 181. The inclined surfaces 183 of teeth 181 and/orbevels 156 of teeth 151 f guide the teeth 181 and 151, 151 f intointerengagement. After the cap has been fully seated on neck 122, it maynot be removed without providing evidence of tampering. Theinterengagement between teeth 151 and 181 prevent unscrewing of the capfrom the container, while the interengagement between the threadsprevents lifting of cap 121 off neck 122.

In another embodiment of the present invention illustrated in FIG. 34,closure 221, hereinafter described in detail, is used with a containerneck 222. Neck 222 has a central opening 223 and a downward-outwardslanted lip flange 224 terminating in a vertical stretch 228. Threads229 extend outward of stretch 228. In the illustrated embodiment, thereare two threads 229 a and 229 b. The finish has twelve threads per inchwith a double lead, each thread being six pitch and extending slightlyin excess of 360° of a full thread. It is to be understood that thethreads may be extended greater than 360° for increased threadengagement. Additionally, the thread leads may be of a different linearthread density (threads per inch). The upper flank 236 of thread 229slants downwardly/outwardly at approximately 45° while the lower flankslants downwardly/inwardly at approximately 10°, permitting the threadson the interior of the cap to slip past the threads on the neck finish.Preferably, the thread apex 238 is made with as large a radius aspossible.

Instead of cooperatively shaped threads on the upper neck stretchportion and the inner surface of the closure, one thread may be replacedby a groove. Further, threads 229 may be interrupted, instead ofcontinuous.

Below the vertical stretch is downward extending locking wall portion240. The locking wall portion has a shoulder stretch portion 242 and alower neck stretch portion 246 offset outwardly relative to the upperneck stretch portion. In the illustrated embodiment, the lower neckportion slants downwardly/outwardly at an angle of approximately 10° andterminates in generally horizontal shoulder 247. A vertical stretch 248depends from shoulder 247. To facilitate gripping of the containerduring filling and loading, vertical stretch 248 may be formed with anumber of bumper ring segments 249 (here shown as four in number).

A number of ratchet teeth 251 project from lower stretch 246 on oppositesides of neck 222. Typically, three teeth 251 are formed on either sideof neck 222, with the total extent of the three teeth beingapproximately 90°. The teeth 251 are shaped to interengage the internalratchet teeth formed on the cap, preventing twisting of the cap relativeto the neck. In the illustrated embodiment, teeth 251 are formed onlower stretch 246. However, in alternative forms of the presentinvention the teeth may be located on shoulder stretch 242,interengaging ratchet teeth formed on the shoulder of the cap, as isdiscussed below.

A cap for use with neck structure 222 is illustrated in FIG. 35 to FIG.40. The cap has top 261 from the periphery of which depends downwardextending upper skirt 262. As illustrated, the top comprises a generallyflat top disk; however, other configurations may be substituted. Theupper edge of upper skirt 262 merges with slanted stretch 263, which inturn merges with upper skirt portion or vertical stretch 264. Aninternal shoulder 265 is formed at the intersection of stretches 262 and263. Members 262, 263 and 264 have radially spaced vertical ribs 266 toenable the user to grip the cap.

Threads 271 a and 271 b, which are selected to mate with threads 229 ofneck 222, are formed on the interior of the skirt. The shape of threads229 a, 229 b, 71 a and 71 b allow the threads to slip passed one anotherand then interengage. Threads 271 a and 271 b are double lead and extendaround the circumference of the cap in excess of 180°, for example,approximately 200°. In conventional capping machines, cap 221 isdeposited on neck 222. Since threads 271 a, 271 b are diametricallyopposed, the cap tends to rest horizontally on neck 222, facilitatingthe application of the cap onto the neck with a downward, axial force.

The closure has ring-like skirt or lower skirt portion 2-70 below upperskirt portion 264. The lower skirt comprises outer skirt portion 274offset outwardly relative to upper skirt portion 264 and a shoulder 273extending inwardly from the upper edge of the outer skirt portion. Afrangible section including a number of radially spaced bridges 276interconnects the shoulder and the upper skirt portion. In theillustrated embodiment, the lower edges of ribs 266 form the bridges.Alternatively, a line of weakness may be formed through the intersectionof shoulder 273 and upper skirt 264.

A number of internal ratchet teeth 281 spaced and dimensioned to matchthe teeth 251 of neck 222 are formed on outer skirt portion 274. Teeth281 are positioned to engage teeth 251 when cap 221 is pushed onto neck222. After cap application, the inner edges 282 of teeth 281 arepositioned close to lower stretch 246. The interlocking engagementbetween the teeth on the cap with those on the neck prevent twisting ofthe cap relative to the container while the lower skirt is intact. Teeth281 are located on the outer skirt in the present embodiment; however,the teeth may alternatively be positioned along the inner surface ofshoulder 273. The teeth formed on the shoulder surface would be shapedand positioned to interengage teeth located on the shoulder stretch ofneck 222. When the closure is applied to the neck, the ratchet teeth onthe opposing surfaces of shoulder 273 and shoulder stretch 42 interlock,preventing removal of the cap so long as the line of weakness is notbroken.

The interengagement between ratchet teeth 251 and 281 prevent twistingof the cap relative to the neck. To remove the closure, the lower skirtmust first be separated from the upper skirt, as by rupturing of thefrangible section, allowing the cap to be unscrewed from the container.The ruptured bridges warn the consumer that the container has beenopened and the contents tampered with. Thus, the interlocking ratchetteeth and frangible bridges of the present invention are atamper-evident features of the present invention.

In the preferred embodiment, a tear tab 286 is connected to the loweredge of outer skirt 274. The tear tab provides means for removing thelower skirt, and may be used to orient cap 221 relative to thecontainer. Lower skirt 270 is formed with a line of weakness generallyindicated by 287 extending through outer skirt 274 and shoulder 273. Theline of weakness facilitates removal of the lower skirt from theclosure, and is another tamper-evident feature of the present invention.When initially opening the container, the consumer pulls tab 286 toremove lower skirt 270, rupturing line 287 and frangible section 276.The absence of the lower skirt more dramatically alerts the consumer topossible tampering of the contents. A distracted consumer may fail tonotice the fractured bridges, therefore the removal of the lower skirtis a more obvious indication of tampering.

It has been contended that the tamper-evident features of the closurewhich has been described up to this point may be circumvented by curlingthe lower skirt 270 in an upward direction. A cap having a partiallydeformed lower skirt is shown in FIG. 34. With the lower skirtcompletely deformed upward, teeth 251 and 281 will no longerinterengage, and cap 221 may be twisted relative to the container forremoval. In practice, this manipulation of the closure will usuallyfracture bridges 276. However, as discussed, the ruptured bridges maynot be readily apparent to the distracted consumer.

To further safeguard the consumer from the dangers of tampering, asubstantially vertical fin 300 is formed between upper skirt 264 andshoulder 273. In one embodiment, vertical fin 300 is located adjacentline of weakness 287, as is shown particularly in FIG. 36, FIG. 37 andFIG. 38. When a dishonest patron attempts to curl the lower skirt 270towards the upper skirt, the deformation of the material below thevertical fin 300, generally indicated at 302, is resisted by the fin.This resistance distorts lower skirt 270, causing line of weakness 287and frangible bridges 276 to rupture, providing evidence of tampering.Attempts by a dishonest patron to tamper with the contents of acontainer by curling the lower skirt to remove cap 221 will be revealedby the fracturing of frangible section 276 and line 287. Thus, verticalfin 300 provides additional protection against tampering.

In the preferred form, fin 300 is formed with a substantially verticalline of weakness 301 through the closure adjacent the upper skirt. Aslower skirt 270 is torn from the closure, line of weakness 301 isruptured and the fin removed from upper skirt 264 together with thelower skirt. The upper skirt is provided with an even, clean finish oncevertical fin 300 is removed. However, if desired, the fin could beformed with a line of weakness extending through the fin adjacentshoulder 273. The fin would then remain intact on upper skirt 264 afterremoval of the lower skirt from the container.

In the alternative embodiment shown in FIG. 43 to FIG. 45, improvedtamper evidence is achieved by a camming action of dual fins 310upstanding from shoulder 273. In this embodiment, the fins need not bejoined to upper skirt 264. If a dishonest patron attempts to curl thelower skirt to tamper with the contents of the container, dual fins 310act as a cam to force the lower skirt radially outward, causingsufficient deformation of the lower skirt to fracture bridges 276 andline of weakness 287. A further advantage of the present embodiment isthat no residual material remains on upper skirt 64 after removal oflower skirt 270.

As is illustrated particularly in FIG. 37 and FIG. 39, line of weakness287 extending through lower skirt 270 is a continuous section ofmaterial. This configuration is preferred as it is simple tomanufacture. However, an alternative embodiment having a gap 304 at theintersection of shoulder 273 and outer skirt 274 is shown in FIG. 41 andFIG. 42. Lower skirt 270 has a groove 306 extending through shoulder 273and outer skirt 274. The shoulder is formed with a first web material308 bridging groove 306, while the outer skirt is formed having a secondweb material 310 bridging the groove. The first and second web materials308, 310 are separated by gap 304.

With the embodiments illustrated in FIG. 35 to FIG. 40 and FIG. 43 toFIG. 45, upward deformation of the lower skirt stretches the lower edgeof the outer skirt, placing the corner between the shoulder and theouter skirt in compression. Removing material from the corner andforming gap 304, as in FIG. 41 and FIG. 42, increases the amount ofdistortion caused by curling the lower skirt, thereby facilitating thefracturing of line of weakness 287. Thus, the alternative embodimentprovides an additional tamper-evident feature of the cap of the presentinvention.

In feeding the snap-on screw-off closure, orientation is generallyachieved by causing tear tab 286 to be at the trailing edge, riding in aslot cutout of the cap feed chute. It has been observed thatoccasionally the lower skirt 270 of a trailing cap will ride up onto theshoulder 273 of the preceding cap directly above the tear tab 286 of thepreceding cap. This causes a jam and stops the flow of caps. It isreadily apparent that an additional benefit of fin 300 and dual fins 310of the present invention is the prevention of the occurrence of jamming.

After the container has been filled, it is transported through a cappingmachine. As is well understood in the bottling art, and in a mannersimilar to that whereby push-on, snap-off caps are applied, caps 221 arefed one at a time out of a bowl in the capping machine, with tear tab286 orienting the caps for uniform discharge in a pre-determinedorientation relative to the containers passing therebelow. Although notshown in the accompanying drawings, each container has a squarecross-section or some other variation from a round shape which permitsthe container to be oriented relative to cap 221. The structure ofcapping machines is well known in the bottling art. Because of therelative orientation of cap 221 and neck 222, teeth 251 and 281 are invertical alignment. An axially downward force is applied to the cap,pushing the cap onto the neck. Threads 271 a and 271 b slip over threads229 a and 229 b, the slanted surfaces 236 facilitating such movement.The cap is sufficiently resilient so that it expands outwardsufficiently to permit the threads to slip. As cap 221 seats on theneck, teeth 281 engage behind teeth 251 to fully engage teeth 281 inplace.

After the cap has been fully seated on neck 222, it can not be removedwithout providing evidence of tampering. The interengagement betweenteeth 251 and 281 prevent unscrewing of the cap from the container,while the interengagement between the threads prevents lifting of cap221 off neck 222. Substantially vertical fin 300 or dual fins 310prevent upward deformation of the lower skirt without rupturingfrangible bridges 276 and line of weakness 287. Thus, any attempts totamper with the contents of the container will be revealed to theconsumer.

When a consumer desires to initially open the container, he grips tab286 and pulls circumferentially around the container causing lower skirt270 and vertical fin 300 to be removed. Ratchet teeth 281 are therebyremoved from interlocking engagement with ratchet teeth 251, providingevidence of tampering and enabling the consumer to unscrew cap 221 fromneck 222. To replace the cap, the consumer merely reverses the directionof twisting.

In another embodiment shown in FIG. 46 and FIG. 47, to further safeguardthe consumer from the dangers of tampering, a plurality of substantiallyvertical castle projections 500 are circumferentially-spaced about theupper skirt 464 extending upwardly from shoulder 473 and spacedoutwardly from upper skirt 464. In the illustrated embodiment, the capis provided with eight castle projections, however, one will appreciatethat the actual number may vary. In the illustrated embodiment, onecastle projection 500′ is located adjacent line of weakness 487, as isshown particularly in FIG. 46 and FIG. 47. When a dishonest patronattempts to curl the lower skirt 470 towards the upper skirt, thedeformation of the material below the vertical castle projection 500 isresisted by the castle projection as it abuts against upper skirt 464.This resistance distorts lower skirt 470, causing line of weakness 487and frangible bridges 476 to rupture, providing evidence of tampering.Attempts by a dishonest patron to tamper with the contents of acontainer by curling the lower skirt to remove cap 421 will be revealedby the fracturing of frangible section 476 and line 487. Thus, verticalcastle projection 500 provides additional protection against tampering.

In the preferred form, castle projections 500 are circumferentiallyspaced about the upper skirt and are spaced away from the upper skirt.On will appreciate that the spacing and height of the castle projectionsmay vary, provided that height of the castle projections is tall enoughto allow camming action in that the upper edge 505 abuts against a lowerportion of upper skirt 464 as lower skirt 470 is pivoted about thefrangible section 476 in the direction of arrow P in FIG. 47. Suchcamming action is similar to that described above with respect to thedual vertical fins 310. In the illustrated embodiment, the castleprojection extends substantially vertically from the lower skirtportion, however, one will appreciate that the shape of the projectionmay vary. For example, the projection may have an outwardly taperedsurface providing a right-triangular cross-section in which the angledsurface is spaced outward from the upper skirt portion. The angledsurface may provide a different aesthetic while the inner verticalsurface still provides the camming action which encouragestamper-evidencing rupture of the frangible section. Alternatively, thecastle projections may be in the form of rod-like extensions whichextend upwardly from the lower skirt.

If a dishonest patron attempts to curl the lower skirt to tamper withthe contents of the container, castle projections 500 act as a cam toforce the lower skirt radially outward, causing sufficient deformationof the lower skirt to fracture bridges 476 and line of weakness 487. Aslower skirt 470 is torn from the closure, frangible section 476 isruptured and the castle projections are removed from upper skirt 464together with lower skirt 470. A further advantage of the presentembodiment is that no residual material remains on upper skirt 64 afterremoval of lower skirt 470.

After the cap has been fully seated on neck 422, it can not be removedwithout providing evidence of tampering. The interengagement betweenteeth 451 and 481 prevent unscrewing of the cap from the container,while the interengagement between the threads prevents lifting of cap421 off neck 422. Substantially vertical castle projection 500 preventupward deformation of the lower skirt without rupturing frangiblebridges 476 and line of weakness 487. Thus, any attempts to tamper withthe contents of the container will be revealed to the consumer.

When a consumer desires to initially open the container, he may merelygrip the upper skirt 464 and twist the cap with respect to the neck tounthread the cap from the container neck. In this case, the frangiblesection will rupture thus allowing the cap to be unthreaded from theneck. Alternatively, the cap may be provided with a gripping tab, asdiscussed above, and pulls circumferentially around the containercausing the lower skirt and vertical castle projections to be removedfrom the remainder of the cap, thereby removing the ratchet teeth of thecap from interlocking engagement with ratchet teeth of the neck,providing evidence of tampering and enabling the consumer to unscrew thecap from the neck. In either case, to replace the cap, the consumermerely reverses the direction of twisting.

The foregoing descriptions of specific embodiments of the presentinvention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteaching. The embodiments were chosen and described in order to bestexplain the principles of the invention and its practical application,to thereby enable others skilled in the art to best utilize theinvention and various embodiments with various modifications as aresuited to the particular use contemplated. It is intended that the scopeof the invention be defined by the claims appended hereto and theirequivalents.

1. A container closure for use with a container neck of the type havingan upper opening, a downward extending upper neck stretch portion belowsaid opening, said upper neck stretch portion having an exterior, atleast one first helical engagement thread around said exterior of saidupper neck stretch portion, a locking wall portion below said upper neckstretch portion, said locking wall portion comprising a lower neckstretch portion offset outwardly relative to said upper neck stretchportion and a first shoulder extending inwardly from said lower neckstretch portion to said upper neck stretch portion, at least oneexternal tooth on said locking wall portion, said closure having a top,a downward extending upper skirt portion depending from said top, atleast one second helical engagement thread around said interior of saidupper skirt portion shaped to mate with said at least one first helicalengagement thread, a lower skirt portion below said upper skirt portion,said lower skirt portion comprising an outer skirt portion offsetoutwardly relative to said upper skirt portion and a second shoulderextending inwardly from said outer skirt portion to said upper skirtportion, a frangible line of weakness interconnecting said upper skirtportion and said second shoulder, at least one castle projection joinedto and upstanding from said second shoulder to prevent upwarddeformation of said lower skirt portion without breaking said frangibleline of weakness, at least one internal tooth on said lower skirtportion shaped to engage said at least one external tooth to preventunscrewing of said closure relative to said neck without breaking saidfrangible line of weakness.
 2. The closure of claim 1 in which saidcastle projection extends substantially vertically from said lower skirtportion.
 3. The closure of claim 1 in which said castle projection isspaced from said upper skirt portion.
 4. The closure of claim 1 in whichlower skirt portion includes a plurality of said substantially verticalcastle projections circumferentially spaced from said upper skirtportion.
 5. The closure of claim 4 in which said lower skirt portion isformed with a substantially vertical line of weakness extending adjacentat least one of said substantially vertical castle projections adjacentsaid upper skirt portion, whereby said at least one substantiallyvertical castle projection is a tamper-evident feature of said closure.6. The closure of claim 1 in which said at least one internal tooth islocated on said outer skirt portion.
 7. A container closure for use witha container neck of the type having an upper opening, a downwardextending upper neck stretch portion below said opening, said upper neckstretch portion having an exterior, at least one first helicalengagement thread around said exterior of said upper neck stretchportion, a locking wall portion below said upper neck stretch portion,said locking wall portion comprising a lower neck stretch portion offsetoutwardly relative to said upper neck stretch portion and a firstshoulder extending inwardly from said lower neck stretch portion saidupper neck stretch portion, at least one external tooth on said lockingwall portion, said closure having a top, a downward extending upperskirt portion depending from said top, said upper skirt portion havingan interior, at least one second helical engagement thread around saidinterior of said upper skirt portion shaped to mate with said at leastone first helical engagement thread, a lower skirt portion below saidupper skirt portion, said lower skirt portion comprising an outer skirtportion offset outwardly relative to said upper skirt portion and asecond shoulder extending inwardly from said outer skirt portion to saidupper skirt portion, a frangible line of weakness interconnecting saidupper skirt portion and said second shoulder, at least one substantiallyvertical castle projection upstanding from said second shoulder toprevent upward deformation of said lower skirt portion without breakingsaid frangible line of weakness, at least one internal tooth on saidlower skirt portion shaped to engage said at least one external tooth toprevent unscrewing of said closure relative to said neck withoutbreaking said frangible line of weakness, said at least one firsthelical engagement thread and said at least one second helicalengagement thread being shaped such that when said closure is moveddirectly axially downward on said neck without relative rotation of saidclosure and said neck, said at least one first helical engagement threadand said at least one second helical engagement thread slip passes eachother and then interengage, said second shoulder and said outer skirtportion are formed with a line of weakness extending through said secondshoulder and said outer skirt portion.
 8. The closure of claim 7 inwhich said at least one substantially vertical castle projection islocated adjacent said line of weakness.
 9. The closure of claim 7 inwhich said line of weakness comprises a groove formed through saidsecond shoulder and said outer skirt portion, said second shoulderformed having a first web material bridging said groove and said outerskirt portion formed having a second web material bridging said groove.10. The closure of claim 9 in which said first and second web materialsare separated by a gap adjacent the intersection of said second shoulderand said outer skirt portion.